As shown in FIGS. 1 and 2, workpiece supporting assembly 100 of the carpenter's plane of the prior art is composed of a slide slot set 110 provided with a first fastening member 115, a fastening seat 120 mounted on the slide slot seat 110, and a grid plate 170 connected with the fastening seat 120 and provided with a lock rod 140 and an angle adjusting member 150. The fastening seat 120 is pivoted by a locking shaft 180 to a pivoting hole of the first fastening member 115. The lock rod 140 is locked by a second fastening member 145 via the fastening seat 120. The fastening seat 120 is adjusted and located by the locking shaft 180 in accordance with the various widths of the wood planing. The bevel of the grid plate 170 is adjusted and located by the second fastening member 145 for locating a wood at various angles.
The prior art structure described above is defective in design in that the simultaneous adjustments of the position of the fastening seat 120 and the bevel of the grid plate 170 are attained by the separate operations of the locking shaft 180 and the second fastening member 145. Such operations are tedious and time-consuming. In addition, the constructions of the locking shaft 180 and the second fastening member 145 result in an increase in the overall cost of making the carpenter's plane of the prior art.